Crossed Food Allergies: Common Reactors, Treatment & Prevention

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When you learn you have or your child has a food allergy, chances are you’ll have some questions. You may be wondering if you have allergies to more than one thing. You might not know when you should start adding certain foods back into your diet or try new foods. These are common concerns — and you’re not the only one having to deal with this. Each person is different and the best approach is to seek individualized recommendations and guidance from your doctor.

One particular type of allergy is a crossed food allergy or cross-reactivity allergy and these allergies can be a little confusing.

What are Crossed Food Allergies?

Cross-reactivity allergies occur when antibodies to a certain allergen react with other allergens from another source thereby producing an allergic reaction to this allergen source too. It’s kind of confusing so to explain it another way: cross-reactivity in allergic reactions happens when the proteins of one particular substance, such as pollen, have similarities to the proteins found in another substance, typical certain foods.

There can be cross-reactions between certain foods and:

  • tree pollen
  • grass
  • ragweed
  • latex
  • other foods

Researchers conducted studies to help allergists determine the related foods of concern and how probable it was for individuals with one particular food allergy to react to another related food type. Allergists can use the information from this research to help them figure out the recommendations and advice they can give their patients about when (and if) they can add certain foods back into their diet and when they can try new foods.

In some cases, this information indicates a good chance of either an allergic reaction occurring or testing positive to an allergy test to new foods with a related protein. For instance, if you have a cashew allergy, you could also be allergic to mangos or pistachios.

There are numerous food families that could link together like this, therefore you should speak with your doctor or allergist to determine the magnitude of your food allergy and if there’s a chance of cross-reactivity.

Common Reactors for Crossed Food Allergies

Some cross-reactive allergens include:

Pollen and Foods

Some people who have an allergy to pollen in the forms of hay fever or allergic rhinitis may develop symptoms inside and around their throat and mouth right after they eat foods containing proteins that are cross-reactive to the pollens. These foods include:

  • Raw vegetables
  • Fresh fruit
  • Seeds
  • Nuts

You refer to this as pollen-food syndrome or oral allergy syndrome.

For instance, individuals who have an allergy to birch pollen could have symptoms immediately after consuming raw:

  • Pitted fruits
  • Peaches
  • Carrots
  • Apples
  • Hazelnuts
  • Peanuts

With this allergy, your symptoms could experience:

  • tingling or itching of the tongue, lips, throat and roof of the mouth.
  • hives around the area of the mouth the food touched,
  • throat tightness 
  • swelling of the tongue and lips.

Less than three percent of people with this type of crossed food allergy experience symptoms that extend beyond the throat or mouth or result in anaphylaxis (acute allergic reaction).

You may be able to tolerate these foods better when you cook them since the pollen cross-reactive food proteins break down when you subject them to stomach acids or heat. So, while you would get an allergic reaction to a raw peach, you may be able to eat a slice of peach pie with no problem.

Latex and Foods

Latex comes from a milk material extracted from the rubber tree. It’s a natural product rubber latex products, including latex balloons and gloves, are made from.  It can also induce various allergic and irritant reactions.

The IgE-mediated latex allergic reaction is the most worrisome type leading to immediate reactions like:

  • Swelling
  • Hives
  • Anaphylaxis
  • Wheezing

Around 30 to 50 percent of individuals with this type of latex allergic reaction have symptoms with various fruits cross-reactive to latex like:

  • Kiwis
  • Bananas
  • Chestnuts
  • Avocados

But, the IgE-mediated latex reaction is rare and those who do report having a reaction usually do so because of contact sensitivity.

Foods and Foods

Cross-reactions can also happen between closely related foods or food groups. Cross reactions can occur in the

The Crustacean Group

  • Shrimp
  • Lobster
  • Crawfish
  • Crab

If you are allergic to one type of crustacean, you have a 75 percent likelihood of being allergic to another type.

The Milk Family

  • Cow’s milk
  • Sheep’s milk
  • Goat’s milk

The risk of allergic symptoms to sheep’s milk or goat’s milk to that of cow’s milk allergy is about 90 percent.

The Legumes Group

  • Peanuts
  • Beans
  • Lentils

Note that if you’re allergic to peanuts, you have only a five percent chance of being allergic to another legume, but a 35 percent risk of a cross reaction to a tree nut. Surprisingly, peanuts are not related to tree nuts (almonds, walnuts, cashews, etc.).

The Fish Family

  • salt water
  • fresh water

You have a 50 percent risk of being allergic to another fish if you are allergic to one species of fish.

The Tree Nut Family

  • Walnuts
  • Pecans
  • Hazelnuts
  • Cashews
  • Brazil Nuts
  • Pistachios
  • Almonds

Hazelnuts, pecans and walnuts form a strong cross-reactive with tree nuts. Almonds, Brazil nuts, cashews, hazelnut, cashew, and pistachio nuts are moderately cross-reactive with tree nuts.

Treatment for Crossed Food Allergies

Cross-reactivity makes food allergy testing and diagnosing a challenge. Doctors approach crossed food allergy treatment and management in a couple ways.

  1. They treat the allergic reactions pharmacologically to relieve the symptoms.
  2. They help prevent an allergic reaction by advising you to avoid the allergenic foods that could cause or do cause a cross reaction.


Your doctor will likely prescribe you anti-histamine since its effective at treating mild to moderate allergic reactions. These medications block tissue histamine receptors.

Adrenaline or epinephrine is a more potent medication that resolves severe anaphylactic reactions. If you have a history of a life-threatening reaction to certain foods, your doctor would likely recommend you carry a syringe filled with epinephrine with you at all times.

Prevention for Crossed Food Allergies

Prevention is the primary approach to treating food allergies. Here, you implement an avoidance diet. So, if you’re allergic to peanuts let’s say, you would avoid all forms of peanuts. With an avoidance diet, you have a huge responsibility where you need to have comprehensive knowledge of the composition of foods.

A dietitian can help you understand food labels so you can determine if a certain food has any ingredients that will set off a reaction. The fewer foods you have to eliminate from your diet the better chances you’ll comply with your avoidance diet. Therefore, it’s imperative your first step is receiving an accurate diagnosis.

When it comes to cross-reactivity and food allergies, individual reactions will vary. Your allergist has experience in the allergen cross-reactivity area and can assist in coming up with an accurate diagnosis. They’ll also provide you with guidance as to which cross-reactive foods you’ll need to eliminate from your diet and ones you can add back in.


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